United's 5000 miles for a roundtrip interisland flight on Aloha is a great deal. If you fly to HNL on United, you more than earn the miles for the free neighbor island trip.
For a bad deal, how about any use of Hhonors points for something other than hotel stays. Try 5000 points for a car rental upgrade - or 15000 points for a dozen Mrs. Fields cookies.